If you follow results of cilantro starting mid Feb 2019 on this blog you will only see that either fresh or fresh frozen cilantro has benefit. Perhaps I missed reading the positive results from those that did the drops, if so please correct me.
All other treatments of which I have a cabinet full of were a waste of time and money- my GD had a predictable rhythm after the first full year of rash it was six months of dormancy and 6 months of activity. My first year was the most severe with all the front and back torso covered, after that the rash area was smaller, not going up to my neck and the pain and itching a few degrees less, still awful.

Honestly I haven't read about GD manifesting on the hands. I have 3 forms of eczema, GD is one yet my first form was Allergic Contact Dermatitis, ACD. The rash was on my hands, between fingers and on my palms. Crazy itching! Steroids did help me temporarily with this form, they are a treatment not a cure. Avoidance to allergens is key. It can happen at any age, but often it occurs in middle age like it did for me. ACD is caused by allergic contacts: fibers, preservatives, adhesives, metals and so on. Everyday chemicals and natural ingredients in clothing, dish soap, bedding, laundry soaps, make up, hand lotions, shoes, anything you have contact with. The 5 Day Extended Patch Test identifies your allergens, Google this test if you haven't already had it. The True Test is a common test kit ordered by specially licensed derms and allergists, not all derms are licensed to administer these test kits. It take 5 full days at a cost of $1,500 but is covered by most insurance and Medicare. It's not unusual to have several forms of eczema which have different causes and treatments. Go to dermnetnz.org and search for ACD and look at the mass of photos they have of your rash areas, you may find one that looks exactly like yours. While you are at it look at the GD rash sites, different types of eczema often have different rash characteristics and locations and I'd be surprised to see any GD hand rashes. For you I wondered about sailing if nylon ropes are used as I am allergic to nylon and also varnishes if you have a wooden tiller. For me toxic Dawn dish soap and using protective gloves with elements of rubber triggered my hand eczema ACD. Preservatives in hand lotions triggered me. Even the memory foam pillow and mattress I had were toxic. My body handled these elements for years but finally overreacted and tried to remove them from my body and thus my histamine army was raised, and this raised my inflammation levels all over my body.